Concrete cutting chain saws are basically structured like conventional chain saws in that a power head drives a sprocket, a bar is mounted to the power head in alignment with the sprocket, and a loop of cutting chain is entrained around the bar and sprocket to be rapidly driven by the sprocket in a circuitous path. Projecting teeth from the saw chain sequentially bite into a surface being cut, each removing small bits of material and collectively cutting a kerf through the material.
The chain consists of numerous individual parts including cutting teeth, side links and center links primarily made of steel and in the case of a concrete saw, the teeth of the cutters have embedded diamond bits. Whereas wood products i.e., trees, are commonly cut with chain saws with a chain lasting for many hours, days and weeks of cutting, as concerns concrete cutting, the cutting chain rapidly wears and has to be frequently replaced at great expense.
A known cause of this rapid wearing is the presence of concrete dust or small particles of concrete that are immersed in water and which form a slurry. The particles in the slurry become injected into the bearing surface areas of the chain. A saw chain is made of many individual links that are interconnected for relative pivoting. Holes formed in the links are aligned fore and aft with holes in preceding and succeeding links, and pins or rivets projected through the holes connect the links together so as to allow relative pivoting. This pivotal action which occurs continuously as the chain is driven around the sprocket and bar produces surface to surface rubbing as between the rivets and the rivet holes for example. Due to the concrete particles being injected between these surfaces, the wearing of the surfaces increases significantly and this wearing induces stretching of the chain as the holes are enlarged. The chain needs to be taut and as it stretches, the chain mount has to be adjusted and such is time consuming. Eventually the chain stretches to a point where it no longer meshes with the drive sprocket and has to be replaced. This often occurs prior to total wearing of the cutting teeth which is normally expected to determine end of life.
It is an object of the present invention to reduce the rate of wearing caused by concrete slurry being injected into the saw chain pivotal joints.